The so-called Head Impact Criterion HIC has been developed as a measure for the risk of injury to a pedestrian. HIC values are calculated as retardation values which are measured when a test body having masses corresponding to an adult head or a child head is shot against the hood at a predetermined speed. In order to be licensed for road traffic, the bodies of newly developed motor vehicles must remain below predetermined HIC limits, which require considerable expenditure on optimization. Conventionally the hood of a motor vehicle comprises an outer skin of sheet metal and a framework located there under, which stiffens the outer skin. The framework is only supported on a supporting structure of the body located there under, at certain points, in particular by means of hood hinges, hood lock, etc. The deformation resistance of the hood in the event of an impact is therefore variable from one place to another depending on how effectively the hood is stiffened by the framework located there under at the place of impact and how far removed the place of impact is from one of the support points of the framework. Each additional stiffening of the hood, which is introduced to increase its deformation resistance in a central region, can have the result that in a region stiffened directly by the framework or located closer to the support points, the stiffness of the hood is too high to satisfy the HIC requirements.
It has been shown that in order to observe the HIC criterion, the hood should initially have a high deformation resistance, which is severely reduced after the onset of deformation. This reduction has the result that after overcoming the initial resistance, the retardation of the impacting pedestrian head is considerably lower than that in the initial phase of the impact. However, the retardation must still be sufficiently strong to completely decelerate the head before a deformation region of the hood is completely used up and the hood impacts against nonresilient vehicle components located there under, in particular against an engine block. In order to still be able to intercept such smashing-through to nondeformable components at the highest possible collision speed, it is important that the available deformation region is utilized as fully as possible.
A body for a motor vehicle is known from the non-prior-published application DE 10 2009 042062.2, in which at least one compressible support is disposed between the framework of the hood and a supporting structure of the motor vehicle to increase the initial deformation resistance of a hood comprising a framework and an outer skin. Tests have shown that in the event of an impact on such a hood, initially the outer skin collapses, whereby a part of the deformation region of the hood is lost and the support is only so severely loaded that it is effectively compressed after collapse of the outer skin.
It is at least one object to further improve the protective effect of such a body. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.